San Diego County Land for Sale

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

Most land for sale in San Diego County is in the unincorporated county, from the semi-rural areas around Fallbrook, Valley Center, Ramona and Alpine to the backcountry and desert, where the County’s General Plan sets how many homes a parcel can hold. The two questions that decide what a parcel is worth to a builder are its General Plan density and its water source: a water district connection, or a well that may fall under the County’s groundwater rules. Septic approval, fire access and whether the parcel was legally created come next.

At a glance

Where to look in San Diego County

The County lists 18 incorporated cities. Everything outside them is unincorporated San Diego County, including Fallbrook, Valley Center, Ramona, Rancho Santa Fe, Alpine, Lakeside, Spring Valley, Bonita, Julian and Borrego Springs. The County’s General Plan, updated in 2011, focuses growth in village cores to protect rural lands and places 80% of planned housing capacity where imported water can be distributed. In practice, land buyers find:

• North County semi-rural areas. Fallbrook, Valley Center and Ramona have acreage, agricultural and estate parcels. The Valley Center and Ramona water districts are among the Water Authority’s listed member agencies, but sewer may not be available, so confirm water and septic for each parcel.
• East County foothills. Alpine, Lakeside and the unincorporated areas beyond El Cajon include rural residential lots and larger parcels, mostly reached by highway (I-8, SR 67).
• Backcountry and desert. Julian and Borrego Springs sit in the lower-density backcountry, where private wells and septic are typical, and Borrego has adjudicated groundwater rights.
• City edges. Some cities have larger lots at their edges, such as Poway real estate, Escondido real estate, San Marcos homes for sale and Vista real estate. Infill lots also come up in San Diego real estate, Santee real estate, El Cajon real estate, Chula Vista real estate and Oceanside real estate. City zoning applies to these, not County rules.

A city name in a mailing address does not prove jurisdiction; our guide to city or unincorporated property shows how to check, and our San Diego County where-to-live guide compares the areas. Agricultural and vineyard buyers can also start with San Diego County vineyards and California agricultural land for sale.

What to check before you buy

General Plan density

In the unincorporated county, the General Plan land-use designation sets the maximum number of homes. Table LU-1 lists:

The Semi-Rural ranges step down with the slope of the site, so a hillside SR-2 parcel can yield fewer lots than its acreage suggests. The County says it has land-use jurisdiction over 772,239 acres, about 35% of the unincorporated area; tribal, state, federal and military lands make up the rest. Zoning must also allow your intended use, so pull both the designation and the zone for the exact parcel. Our parcel jurisdiction and services guide shows where to look.

Legal lot and private roads

Confirm the parcel was legally created. Under Government Code 66499.35, an owner or a buyer under contract can ask the County for a certificate of compliance with the Subdivision Map Act. If the parcel does not comply, the County issues a conditional certificate, and its conditions must be met before a later development permit.

If you plan to subdivide, the County’s tentative map conditions allow private road easements at least 40 feet wide under the San Diego County Standards for Private Roads, and each dead-end private road easement needs a cul-de-sac that meets those standards. For an existing shared road, ask for the recorded easement and any maintenance agreement; see private road maintenance agreements.

Water: district connection or well

The San Diego County Water Authority wholesales water to member agencies, which serve customers and set connection rules. Outside those agencies, a parcel depends on a well or a small water company. The County’s Water Well Program requires a permit to install or modify a well and regulates well design, construction, modification and destruction. It lists separate new permitting requirements for the Upper San Luis Rey Valley Groundwater Basin and the Borrego Springs Subbasin, and notes that the drought-era Executive Orders N-7-22 and N-3-23 stopped applying on September 4, 2024.

The County’s Groundwater Ordinance, first adopted November 15, 1991 and last amended March 1, 2013, governs projects that rely on groundwater. In the Borrego Basin, a 2021 court judgment adjudicated groundwater rights, and the County’s page says all groundwater users there must have rights; projects must show they can obtain them before approval. The County’s updated groundwater guidelines also address the San Pasqual Valley and Upper San Luis Rey Valley basins, where projects must not impede sustainable management under the basin’s groundwater plan. If a parcel will use a well, ask for the well completion report and a recent yield and quality test, and budget time for any groundwater study a discretionary permit requires. Our rural water and wastewater guide lists the records to request.

Septic

Outside sewer service, the County’s Department of Environmental Health and Quality regulates septic systems, including design review, installation inspections, percolation tests and repair permits. It keeps septic design records for permitted properties, available through its document library or a public records request. On vacant land, a percolation test is often the first study to order, because it can decide where the house and leach field go.

Fire safe roads and driveways

The Board of Forestry’s State Minimum Fire Safe Regulations, effective April 1, 2023, apply in the State Responsibility Area and, for approvals after July 1, 2021, in Very High Fire Hazard Severity Zones. They cover new parcels, use permits, road construction and building permits for new construction unrelated to an existing structure (14 CCR 1270.03). Roads generally need two 10-foot traffic lanes; driveways need a 10-foot lane with 14 feet of horizontal and 13 feet 6 inches of vertical clearance. Dead-end roads are capped at 800 feet for parcels under 1 acre, 1,320 feet for 1–4.99 acres, 2,640 feet for 5–19.99 acres and 5,280 feet for 20 acres or more. Local fire codes can add requirements. Fire hazard zoning also affects insurance; see wildfire, insurance and access evidence.

Coastal Zone

Coastal parcels, most of them inside the coastal cities, can need a coastal development permit for new construction. See our guide to Coastal Zone property records.

Agricultural land and the Williamson Act

Some agricultural parcels are under Williamson Act contracts. Under state law, a contract runs for at least 10 years and adds a year automatically unless notice of nonrenewal is given (Government Code 51244), and it binds all later owners (Government Code 51243). A contract lowers the assessment but restricts use, so ask whether the parcel is in an agricultural preserve or under contract and get a copy. See our Williamson Act guide and our acreage ownership budget.

Questions people ask

How many homes can I build on rural land in San Diego County?

It depends on the General Plan designation. Rural Lands allow 1 home per 20, 40 or 80 gross acres; Semi-Rural designations range from 1 per 0.5 acre to 1 per 20 acres, depending on the designation and slope.

Do I need a permit to drill a well in San Diego County?

Yes. The County’s Department of Environmental Health and Quality requires a permit to install or modify a well, with added requirements in the Borrego Springs and Upper San Luis Rey basins.

Can I use groundwater on land in Borrego Springs?

Only with groundwater rights. The Borrego Basin was adjudicated in 2021, and the County’s page says all groundwater users there must have rights.

Will vacant land in the backcountry need septic?

Usually, where there is no sewer. The County regulates septic design, percolation tests and installation inspections.

What road standards apply to a new home on rural land?

In the State Responsibility Area and Very High Fire Hazard Severity Zones, the State Minimum Fire Safe Regulations set road widths, driveway clearances and dead-end limits, and local fire codes can add more.

Is land in Fallbrook or Ramona under County rules?

Yes. Both are unincorporated communities, so County planning, permits and the General Plan apply.

How do I confirm a parcel is a legal lot?

Request a certificate of compliance from the County under Government Code 66499.35, or confirm the parcel appears on a recorded final or parcel map.

Sources & notes

1. County of San Diego: County overview.
2. County of San Diego PDS: General Plan and Table LU-1.
3. County of San Diego PDS: Groundwater Ordinance.
4. County DEHQ: Water Well Program and Septic systems.
5. San Diego County Water Authority: Member agencies.
6. San Diego County Code of Regulatory Ordinances: tentative map conditions (American Legal Publishing).
7. Board of Forestry: OAL approval, State Minimum Fire Safe Regulations; 14 CCR 1270.03, 1273.01 and 1273.08 (Justia copies).
8. California Government Code 51243, 51244 and 66499.35.
9. San Diego County Assessor/Recorder/County Clerk: Recording.

Notes: Slope ranges for Semi-Rural densities (Table LU-2), zoning minimum lot sizes, the County’s agricultural preserve policy, the County fire code’s road standards and well and septic fees were not verified for this page. The groundwater page describes a 2023 amendment process; confirm the ordinance’s current text with Planning & Development Services. Statute sections were read on mirror sites and are linked to leginfo. Rules change; verify before you buy.

General information, not legal, tax or lending advice. Updated November 2026. Primary sources are linked in this guide.

Related: San Diego County homes · Where to live in San Diego County · Buying land in California · Unincorporated San Diego County · Rural home comparable sales